Is there a better (nicer) way to write this if statement?
if(string1 == null && string2 == null && string3 == null && string4 == null && string5 == null && string6 == null){...}
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1if(String.IsNullOrWhiteSpace(string1)&& ... -> so you don't only check for null Strings, but also for empty and some containing only spacesOffler– Offler2013-02-20 14:42:39 +00:00Commented Feb 20, 2013 at 14:42
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3Do you really need so many separate string variables? Can you not make an array or list of strings and use that instead? It will most likely simplify a lot of other operations as well.John Willemse– John Willemse2013-02-20 14:43:11 +00:00Commented Feb 20, 2013 at 14:43
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1With the information you've given, no, not really (I guess you can break it over several lines if that helps you), but @JohnWillemse point stands. If you need that many string variables, maybe you need to think about using some different data structure that can encapsulate this logic.Matt Burland– Matt Burland2013-02-20 14:44:53 +00:00Commented Feb 20, 2013 at 14:44
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Personally I'd just write it exactly like that. Although I don't think I'd ever have that many strings to test for nullness without them being in some kind of collection.Matthew Watson– Matthew Watson2013-02-20 14:59:53 +00:00Commented Feb 20, 2013 at 14:59
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Thank you all for your answers. Using list is a good idea, but I also like Tim's solution with null-coalescing operator, so I accepted his answer.Dušan– Dušan2013-02-21 11:31:11 +00:00Commented Feb 21, 2013 at 11:31
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8 Answers
Perhaps using the null-coalescing operator(??):
if((string1 ?? string2 ?? string3 ?? string4 ?? string5 ?? string6) == null){ ;}
If all strings are in a collection you can use Linq:
bool allNull = strings.All(s => s == null);
Comments
You could put all the strings in a list and use
if(listOfStrings.All(s=>s==null))
At the very least you can put it on multiple lines
if(string1 == null
&& string2 == null
&& string3 == null
&& string4 == null
&& string5 == null
&& string6 == null)
{...}
If you made a function like this:
public static bool AllNull(params string[] strings)
{
return strings.All(s => s == null);
}
Then you could call it like this:
if (AllNull(string1, string2, string3, string4, string5, string6))
{
// ...
}
Actually, you could change AllNull() to work with any reference type, like this:
public static bool AllNull(params object[] objects)
{
return objects.All(s => s == null);
}
2024 Update for .NET 9/ C# 13:
Now we have both nullable annotation and params collection, so we can write AllNull() like so:
public static bool AllNull(params Span<object?> objects)
{
foreach (var obj in objects)
{
if (obj is not null)
return false;
}
return true;
}
This has the advantage that you can call it passing a list of reference objects without the compiler having to allocate an array and pass it to the AllNull() method, which could be a lot more efficient.
You can also implement it using IEnumerable<object?>:
public static bool AllNull(params IEnumerable<object?> objects)
{
return objects.All(s => s == null);
}
This allows even more collection types to be passed to it (but it will usually not allow the same level of optimisation as using Span<object?>.)
3 Comments
PM.
Nice and clean solution!! Though similar to @Tim Schmelter solution, made it way easy by separating it in function and providing a complete example.
Matias Masso
Great answer. I would just suggest to use nullable objects array (params object?[] objects)
Matthew Watson
@MatiasMasso Updated for C# 13 (ten years later ;))
string[] strs = new string[] { string1, string2, string3 };
if(strs.All(str => string.IsNullOrEmpty(str))
{
//Do Stuff
}
Or use strs.All(str => str == null) if you don't want to check for empty strings.
Comments
Make a IEnumerable of strings (list or array....), then you can use .All()
var myStrings = new List<string>{string1,string2,string3....};
if(myStrings.All(s => s == null))
{
//Do something
}
3 Comments
Jim Mischel
Or in a single line ...
if (Enumerable.All(new string[] {str1, str2, str3, str4}, s => s == null))
Tim Schmelter
@JimMischel: This creates an additional collection just to shorten an evaluation. Btw, it does not even really shorten it.
Jim Mischel
@TimSchmelter: Yes, it does create an additional collection, as does the answer that you upvoted.
Well, I don't know if it is nicer or better, or not, you can use IEnumerable.Any method like this;
Determines whether a sequence contains any elements.
List<string> list = new List<string>{"string1","string2","string3", "string4", "string5"};
if(list.Any(n => n == null))
{
}
And you can use Enumerable.All() method like;
Determines whether all elements of a sequence satisfy a condition.
if (Enumerable.All(new string[] { string1, string2, string3, string4, string5 }, s => s == null) )
{
Console.WriteLine("Null");
}
Comments
In case you want to check null or empty, here is another way without arrays:
if (string.Concat(string1, string2, string3, string4, string5).Length == 0)
{
//all null or empty!
}
1 Comment
Tim Schmelter
Does not check if all are null, the same as with Dennisch's answer.
This should do the same:
if (string.IsNullOrEmpty(string1 + string2 + string3 + string4 + string5 + string6)){...}
